Economic analyses are critical to understanding the relationship between resource use, treatment planning, and outcomes of substance abuse treatment. Developing methods to obtain precise cost estimates while balancing limited research funds is one important component for conducting these analyses. As a new investigator to the field completing a "three-paper" dissertation requirement of the PhD in Social Policy at Brandeis University, I am proposing to conduct and expand one of the proposed dissertation studies under this grant application. While the full dissertation involves components pertaining to cost measurement, cost function modeling, and cost-effectiveness analysis, this proposal focuses on the issue of cost measurement. More specifically, this project will involve both a broad conceptual analysis of different costing methodologies as well as an empirical reliability study of a brief, telephone-based, cost analysis instrument (Cost Data Audit Instrument, CDAI) used in the Alcohol and Drug Services Study (ADSS). The CDAI uses an Excel workbook to simultaneously obtain data, report consistency and unit costs, and provide feedback. The conceptual analysis will contain a thorough review of the objectives, administration, and content of various costing methodologies in the field. The empirical analysis will involve collecting substance abuse treatment cost data from 50 substance abuse treatment programs to compare the results of the CDAI to the results of the Drug Abuse Treatment Cost Analysis Program (DATCAP). Differences will be examined in all major component features of the CDAI and the DATCAP on both detail and composite measures of client volume, counseling activities, personnel costs, and non-personnel costs. All facilities will be involved in participating in a program -specific "reconciliation process" to identify from a program perspective, strengths and problems areas in the two instruments, and to resolve differences in the results. Finally, this study will recommend ways for refining cost analyses for the next generation of costing studies.